The Sun on Sunday's sale drifted further downwards last month. At an average sale of 2,297,441 copies during April, it was almost a million fewer than its first full month of sale in February.

However, its major red-top rivals have nothing to celebrate. The Sunday Mirror fell back to 1,088,354, which meant it was selling fewer than a year ago.

Similarly, The People, with an audited sale of 461,973, sold almost 4% fewer than it did in April 2011.

In other words, the two Trinity Mirror titles have lost all the gains they made following the News of the World's closure last July.

Similarly, the Daily Star Sunday has managed to cling on to very few of the Wapping refugees. It sold 482,225 copies in April as compared to 703,631 in July 2011.

The middle market Sundays have also had a poor 12 months. The Sunday Express sold 12% fewer this April compared to the last, while the Mail on Sunday lost 7.5% of its sale.

However, the most spectacular circulation collapses have been among the serious titles. The Independent on Sunday's average sale in April, at 121,837, was down 21% year on year. And The Observer, with 252,642 sales, was down more than 16%.

The Sunday Telegraph also recorded a loss of more than 10%.

By contrast, the Sunday Times, which was still selling more than 1m this time last year, lost a further 6% year-on-year to register a sale of 955,248, which was a slight improvement on the previous two months.